You can see the below link:-
http://www.telerik.com/community/forums/aspnet-ajax/grid/nested-radgrid.aspx
http://www.telerik.com/community/forums/aspnet-ajax/general-discussions/accessing-selected-row-in-nested-radgrid-on-client.aspx
http://www.telerik.com/community/forums/aspnet-ajax/general-discussions/bind-datasource-to-nested-radgrid-codebehind.aspx
http://www.telerik.com/community/forums/aspnet-ajax/grid/nested-radgrid-s-mastertableview-disappears.aspx
http://www.telerik.com/community/forums/aspnet-ajax/grid/radgrid-inside-nestedviewtemplate-of-another-dynamic-radgrid.aspx

Happy Coding.
If it helps you or directs U towards the solution, MARK IT AS ANSWER

For rad control
http://demos.telerik.com/aspnet-ajax/grid/examples/hierarchy/nestedviewtemplate/defaultcs.aspx
http://demos.telerik.com/aspnet-ajax/grid/examples/programming/detailtabledatabind/defaultcs.aspx